Inghottse electric



Aug. 25, 1925. 1,551,297

' D C. LE G. FORTESCUE RELAY Filed Jan. 142, 1920 Zero line of currp'znffhgu vacuum Tube.

WITNESSES: INVENTOR y a W Char/e6 Lefffiriscue.

1 BY U AT1I'ORNEY Patented Aug. 25, 1925.

UNITED STATES PATENT OFFICEL CHARLES LE G. FORTECUE, DIP PITTSBURGH,PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE EIIIJQC'LIRIG 6c MANUFACTURINGCOMPANY, A CORPORATION OF PENN- SYLVANIA.

RELAY.

Application tiled January 12, 1920. Serial No. 350,800.

To all whom it may concern:

Be it known that I, CHARLES Ln G. Fon'rns- CUE, a subject of the King ofGreat Britain, and a resident of Pittsburgh, in the county of Alleghenyand State of Pennsylvania, have invented a new and useful Improvement inRelays, of which the following is a specification.

My invention relates to relays and particularly to amplifying relays forquick-acting interrupters.

One object of my invention is to provide a relay that shall be adaptedto distinguish between a-short circuit and a heavy overload in itsoperation.

Another object of my invention is to provide a device of the aboveindicated character for the control of a circuit interrupter that shallbe especially sensitive in the event that a. short circuit occursthereon.

Another object of my invention is to providea controlling or relaydevice, of the above indicated character, that shall be simple andcompact in construction and sensitive and reliable in operation.

-There are alarge number of limiting features in the design ofquick-acting devices. for use with circuit interrupters that have beenproposed in the past. One of the main difficulties with such devices hasbeen to obtain a. relay circuit that shall be properly selective, thatis, one which can discriminate between an impulse caused by a shortcircuit and an impulse caused by the switching of heavy loads. Thecharacteristic of the former impulse is an abrupt change of voltageacross an inductor that is connected in series with the circuit, whilethe characteristic of the latter impulse is a comparatively gradualincrease in voltage across the inductor.

In view of these characteristics, I propose to. use a three-elementvacuum tube that shall be connected across the terminals of an inductorof the circuit. I provide, further, a. source of energy that shall be socontrolled by the vacuum tube as to actu- I voltage across the inductorbefore the short- .circuit current traverses the circuit.

Fig. 1 of the accompanying drawings is a diagrammatic view of a circuitembodvmg my invention; Fig. 2 is a diagram illiis trating the change involtage across the termmals of an inductor in the circuit caused by ashort circuit thereon, and Fig. 3 1s a diagrammatic view of the circuitshown 1n Fig. 1, illustrating the connections of a condenser thereto.

A direct-current circuit 1 is supplied with energy from a source 2 ofelectnomotive force and is provided with a circuit interrupter 3. A.reactor 4 is connected in series with the circuit 1 and has the cathodeelement 5 and the grid element 6 of a threee-lement vacuum tube 7connected across its terminals. The anode element 8 of the vacuum tube 7is connected to one terminal of the trip coil 9 of the circuitinterrupter 3, the other terminal of which is connected to one terminalof a source 10 of electro motive force. The other terminal of the source10 of electromotive force is connected to the cathode element 5 of thevacuum tube 7. An auxiliary source 11 of electromotive force is employedto energize the cathode element 5. In the system illustrated in Fig. 3,the cathode element 5 and the grid element 6 of the vacuum tube 7, areconnected, in series with a condenser 12. across the circuit 1.

When normal conditions obtain in the circuit 1, the potential differenceacross the terminals of the reactor 4 is so small that the potential ofthe grid element 6 is not raised suiiiciently to provide an appreciableanode current. The occurrence of a short circuit, however, suddenlyincreases the potential difference across the reactor 4, and.consequently, raises the potential of the grid element 6. The gridelement 6, by virtue of its increase in potential, increases theelectron flow through the tube 7, and a current passes therethrough fromthe source 10 of elect-romotive force that is of suflicient value toactuate the trip mechanism 9* of thecircuit interrupter 3 through thetrip coil 9.

In the diagram of Fig. 2, the downward curve showsthe sudden change inpotential across the reactor 4 that is effected. by a short circuit, andthe sh' upward curve shows the sudden incre current that is I permittedto traverse thevacuum tube 7.

Since [the change. in current through the reactor 4 by'switching on ofheavy load is gradual and reaches a steady value, the grid element 6 isnot energized sufliciently to produce an appreciable electron flow. Thevacuiun tube is thus able, in co-operation with a reactor, to eflectselective action and, thus to actuate the circuit interrupter only whena short circuit. occurs thereon. system is shown in Fig. 3 that utilizesa condenser 12 instead of a reactor, as in the system shown in Fig. 1.

Although I have shown a plurality of systems embodying my invention,they are not so limited, as various changes may be made in thearrangement of the elements thereof without departing from the spiritand scope of the invention as set forth in the appended claims.

I claim as my invention:

1. In an electric circuit, the combination with a circuit interrupter,of a vacuum valve for tripping the circuit interrupter only when a shortcircuit occurs on the circuit.

2. In an electric circuit, the combination with a circuit interrupter,of a reactor in the circuit, a vacuum tube connected to the reactor, anda source of energy controlled by the tube for tripping the circuitinterrupter.

3. In an electric circuit, the combination with a circuit interrupter,and tripping means therefor, of an inductor connected to the circuit, avacuumtube connected to the inductor, and a source of energy socontrolled thereby as to trip the circuit interrupter when ashort-circuit occurs thereon.

4. In an electric circuit, the combination with a circuit interrupter,of a reactor connected in the circuit, a vacuum tube operativelyconnected to the reactor, means for energizing the tube, and meanscontrolled thereby for tripping the circuit interrupter.

5. In an electric circuit, the combination with a circuit interrupter,of a reactor operatively connected to the circuit, a vacuum tube adaptedto select voltage changes across the reactor, means for energizing thetube, and means controlled thereby in accordance with the selectedvoltage changes for tripping the circuit interrupter.

6. In an electric circuit, the combination with a circuit interrupter,of a reactor operatively connected to the circuit, and a vacuum tubedisposed with respect to the reactor to so distinguish between 'shortcircuits and sudden heavy-load conditions as to actuate the circuitinterrupter upon an occurrence of a short-circuit condition.

7. In an electric circuit, the combination with a circuitinterrupter,'of a reactor connected to the circuit, a vacuum tube and a.source of energy so disposed with respect thereto as to actuate thecircuit interrupter only upon a predetermined rate of change of currentin the circuit.

8. In an electric circuit, the combination with a circuit'interrupter,of a reactor connected to the circuit, a vacuum tube connected thereto,and a source of energy controlled by the vacuum tube for actuating thecircuit interrupter u on a rate of change of current above a preetermined value.

9. In an electric circuit, the combination with a circuit interrupter,of a vacuum tube, a source of energy controlled thereby for actuatingthe circuit interrupter, and means for operatively energizing the vacuumtube only upon a rate of change of current above a predetermined value.

10. In an electric circuit, the combination with a circuit interrupter,of an electron tube for controlling the interrupter, and means forrendering the tube operative upon a rate of change of current in thecircuit above a predetermined value.

11. In an electric circuit, the combination with a circuit interrupter,of a vacuum tube for controlling the interrupter, said tube beingarranged to permit a suflicient flow of current to trip the interrupteronly when a short circuit obtains on the circuit.

12. In an electric circuit, the combination with an electro-responsivedevice, of an electron-emission device for controlling theelectro-responsive device, and means for so controlling theelectron-emission device as to cause current to traverse theelectro-responsive device only under predetermined conditions in theelectric circuit.

13. In an electric circuit, the combination with an electro-responsivedevice, of an electron-emission device for controlling theelectro-responsive device, and means for so controlling theelectron-emission device as to cause current to traverse theelectroresponsive device only when a short circuit obtains on theelectric circuit.

14. In an electric circuit, the combination with an electro-responsivedevice, of an electron-emission device for controlling theelectro-responsive device, and means con nected to the circuit forimpressing a sulficiently high potential on the electron-emission deviceto effect operation thereof only when a short circuit obtains on thecircuit.

15. In an electric circuit, the combination with a circuit interrupterof an asymmetric valve for controlling the interrupter, and means forenergizing the valve in accordance with the rate of change of currenttraversing the circuit.

16. An interrupter for an electric circuit comprising a. vacuum valveand means for rendering the energization thereof dependout upon apredetermined relatively quick rate of electrical change in the circuitfor contro the interru r.

17. An mterrupter or an electric circuit comprising an asymmetric valveand means for rendering it operative in response to a predeterminedrelatively quick rate of circuit from short circuit currents which,

change in the circuit current for con-trolling the interrupter.

18. The method of protecting an electric consists in controlling avacuum valve in accordance with the rate of electrical change in thecircuit and then controlling the'circuit in accordance with the degreeof energization of the valve.

19. The method of protecting an electric circuit from short circuitcurrents, which consists in controlling a. vacuum valve in accordancewith the rate of change of current in the circuit and then causing thevalve to control the circuit in accordance with such rate of change ofthe current.

20. The method of protecting an electric circuit from short circuitcurrents, which consists in controlling a vacuum valve in accordancewith the rate of change of voltage between two points of the circuit andthen causing the valve to control the circuit in accordance with suchrate of change.

21. In an electric circuit, the combination with a circuit interrupterand a trip coil therefor, of a valvedevice operatively connected to thecircuit for so controlling the current to thetrip coil from the circuitthat current traverses the trip coil only under predetermined loadconditions in the circuit.

22. In an electric circuit, the combination with a circuit interrupterand a trip coil therefor, of a vacuum valve device operatively connectedto the circuit for con-trolling the current to the trip coil.

23. In an electric circuit, the combination with a circuit interrupterand a trip coil therefor, of an asymmetric valve device operativelyconnected to the circuit for controlling the current to the trip coil.

24. The combination with an electric circuit and an interruptertherefor, of a trip coil for the interrupter, an asymmetric valve deviceconnected in series with the trip coil for controlling the same, andconnections between said valve device and the circuit.

25. The combination with an electric circuit and an interruptertherefor, of a trip coil for the interrupter, an electron tube connectedin series with the trip coil for controlling the same, and connectionsbetween said electron tube and the circuit.

26. The combination with an electric circuit and an interrupter thereforhaving a trip coil, of an electron tube controlled in accordance withthe current in the circuit, said trip coil being connected to said tube.

27. The combination with a circuit interrupter having a trip coil, of ahot-cathode valve connected in series with the trip coil and means forvarying the cathode current dependent upon the current traversing saidinterrupter.

28. The combination with a circuit interrupter having a trip coil, of anelectron tube having an anode, a. cathode and a grid, said trip coilbeing connected to the anode, and means whereby the potential of saidgrid is varied in accordance with the current traversing saidinterrupter.

29. The combination with a circuit interrupter having a trip coil, of anelectron tube having an anode, a cathode and a grid, said trip coilbeing connected to the anode, and means including a reactance devicewhereby the potential of said grid is varied in accordance with thecurrent traversing said interrupter. I

30. In combination, a circuit interrupter, an electron tube associatedtherewith, and means including said electron tube for tripping saidcircuit interrupter under predetermined conditions.

31. In combination, a switch, an electron tube associated therewith, andmeans including said electron tube for actuating said switch underpredetermined conditions.

32. In combination, a circuit interrupter,

an electron tube associated therewith, and means including said electrontube for tripping said circuit interrupter, said means being dependentupon the current through said interrupter.

In testimony whereof, I have hereunto subscribed my name this 18th dayof December 1919.

CHARLES LE G. FORTESCUE.

